You will first need to install Alloc's server fixes from the mod manager, make sure you choose the right version for your server.

It will create a new webpermissions.xml located in your saves folder.

Once Alloc's is installed go to Configuration files and click Text Editor next to webpermissions.xml.
See below for an explanation on permission levels

These are the the commands/how it looks in the xml. 2000=public 1000=for anyone signed in via steam, rest are all based on permission level setup in serveradmin.xml

"web.map" = the map itself
"webapi.getstats" = shows in game day and time
"webapi.getlandclaims" = able to see landclaim locations
"webapi.getplayerinventory" = see a player's inventory
"webapi.getplayerslocation" = able to see player locations (offline or online)
"webapi.getplayersonline" = shows players, listed in the players tab, along with details such as SteamID, entity ID, time played, last time online.

*NOTE* if you have done the steps above and still cannot see your map, make sure the map entry doesn't look like this <!-- <permission module="web.map" permission_level="2000" /> --> Because Anything between <!-- --> is considered a comment and is not active **